Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 2/5] srcu: Prevent sdp->srcu_gp_seq_needed_exp counter wrap | Date | Mon, 26 Feb 2018 13:56:29 -0800 |
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From: Ildar Ismagilov <devix84@gmail.com>
SRCU checks each srcu_data structure's grace-period number for counter wrap four times per cycle by default. This frequency guarantees that normal comparisons will detect potential wrap. However, the expedited grace-period number is not checked. The consquences are not too horrible (a failure to expedite a grace period when requested), but it would be good to avoid such things. This commit therefore adds this check to the expedited grace-period number.
Signed-off-by: Ildar Ismagilov <devix84@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/rcu/srcutree.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 01f4a8bf0e03..bb9607baad9b 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -579,6 +579,9 @@ static void srcu_gp_end(struct srcu_struct *sp) if (ULONG_CMP_GE(gpseq, sdp->srcu_gp_seq_needed + 100)) sdp->srcu_gp_seq_needed = gpseq; + if (ULONG_CMP_GE(gpseq, + sdp->srcu_gp_seq_needed_exp + 100)) + sdp->srcu_gp_seq_needed_exp = gpseq; spin_unlock_irqrestore_rcu_node(sdp, flags); } } -- 2.5.2
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